Saturday, September 21, 2013

More Flower Beds, Rock Walls...and Ultrarunning

I just posted a couple weeks ago, here, about a major new landscaping effort in our yard.

Well, I'm nearly done with another, and am proud of the dry stone wall I used to terrace the bed to mitigate the slope of our front yard:

[image credit Gary]

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The wall is about 2' high at its highest. The stones are all local limestone (Franklin County, PA is almost inundated with the stuff) that I snag from farmers' fields, their rock piles, wooded areas, etc.

Some of the largest stones came from the foundation of a particular nearby barn that was destroyed by fire. I made a number of trips gleaning rocks from that source, and some of them still bear the whitewash that was used on the inside walls of the barn. In my wall I made sure to place those stones prominently and not to cover up the whitewash, so I will remember that these stones were once part of a barn and now have a second life in my wall rather than being bulldozed for fill.

The link to Ultrarunning is that whenever I run I am on the lookout for wall stones. When I find a decent rock, meaning having at least one flat side and say up to the size of a microwave, I pull it to the edge of the road and go back for it later in my pickup. When I use the example of a microwave, a stone much beyond that in size I simply cannot lift because this particular geologic formation, the Chambersburg Limestone, is quite dense, checking in at approx 166 lbs per cubic foot.

I've done a bunch of dry stone walls in my life, and the two main "secrets" I've learned:

Stagger the joints (for strength and better appearance)

Lean the wall inward 10-15 degrees to compensate for the outward hydraulic pressure of wet soil

Bear with me for some simple physics. Since dry topsoil weighs approx 2000-2500 lbs per cubic yard--that's better than a ton, people--imagine its weight when it gets wet. There is enormous pressure against the inside of your wall, trying to force it out. You equalize the game in two ways: by the sheer volume, bulk and weight of your wall stones (the bigger, the better) and by the inwards lean.

Oh, and one other tip that I forget to include in my previous post, but it's relevant here: when you mulch, go deep. I use shredded bark that I get by the truckload, and I go at least 4" deep. The mistake many people make is to scrimp on the mulch, going only an inch or two deep...then wonder why they get weeds.